Television – Stereoscopic
Reexamination Certificate
2000-06-30
2001-09-11
Kelley, Chris (Department: 2613)
Television
Stereoscopic
C345S087000
Reexamination Certificate
active
06288741
ABSTRACT:
OBJECT OF THE INVENTION
As expressed in the title of this specification, the present invention refers to an electronic stereoscopic system, whose purpose consists of providing three-dimensional images upon applying it to the television, cinematographic or other audiovisual means, without the viewer having to use special complementary glasses and without the need of the viewer having to make special visual efforts to perceive the three-dimensional effect of the image.
BACKGROUND OF THE INVENTION
Natural three-dimensional vision is produced by each eye perceiving the image of the objects from a view point slightly different from that of the other eye of a specific person, allowing depths and reliefs to be perceived, after the corresponding integrating and processing of the images in said person's brain.
Different systems in order to adapt three-dimensional images previously registered in a special way, and which try to imitate natural three-dimensional vision, are known.
Since photography and cinematography have come into existence, an infinite number of ways to reproduce and view three-dimensional images has been sought.
The simplest systems consist of taking two simultaneous photographs of a single object from slightly different angles, so that the two lenses of the corresponding cameras have a separation equivalent to that between a person's eyes. Subsequently, once the two photographs are developed they are placed on a plane with an opaque barrier perpendicular to said plane and the viewer brings his face towards this barrier in such a way that his right eye only sees the photograph that corresponds to it and his left eye only sees the other photograph, thus obtaining the three-dimensional effect.
Anaglyphs, that are produced by means of printing stereographs in the form of superimposed images of two complementary colors, for example, red and green, are known. For three-dimensional vision, some glasses with filters of said two colors are used, each one of them over each eye, so that each eye only sees the stereo image that corresponds to it.
On the other hand, there are systems of polarized light in which two beams are projected on a screen, one of them polarized vertically and the other one polarized horizontally, thanks to some filters coupled to the projection lenses. The viewers have to wear polarized glasses whose planes are oriented in such a way that each eye receives only the image that corresponds to it. An example of another system based on polarization is disclosed in EP-A-0233636.
There are also autostereoscopic three-dimensional viewing means, which are those in which the viewer does not need any complementary glasses or viewing device. Among these methods are holographs, which are photographic techniques which use laser light; magic images which are those in which the image is broken down and the three-dimensional effect appears before a specific focus by the viewer; and parallactic stereograms which is the system that is the most similar to the present invention.
In parallactic stereograms, a grating of lines or traces in contract to the emulsion acts as a mask, allowing separate registering of the left and right images as a series of vertical lines. The positive transparency is projected on the screen through a similar grating, in such a way that each eye only sees the appropriate image. A normal grating produces the loss of a large amount of light (
805
), therefore, almost all the modern systems use gratings formed by cylindrical and fine lenses. Parallactic systems are disclosed in, for example, JP-A-2-14697 and EP-A-262955.
SUMMARY OF THE INVENTION
In order to achieve the aims indicated in the section “OBJECT OF THE INVENTION”, said invention consists of an electronic stereoscopic system as claimed that is a type of parallactic stereograph but obtained electronically and achieving a greater image resolution. For this purpose, the invention uses a characteristic of liquid crystal screens. Said characteristic is the possibility of changing the viewing angle of the projected image, by means of varying the voltage in these liquid-crystal screens.
A liquid-crystal screen of the type that portable computers use is comprised of a matrix of thousands of light spots called pixels. The viewing angle of the image that these pixels provide is reduced and their projecting directionalization can be electronically varied by-means of the voltage fed to the same.
If with a liquid-crystal screen the same angles and directions as those of a parallactic system are reproduced pixel by pixel, a three-dimensional effect similar to said system is obtained.
The invention excels the clearness of the parallactic system without reducing resolution from the image. For this purpose, the images of the liquid-crystal screen are directed electronically and successively towards the viewer's right eye and left eye at a rate rapid enough so that said viewer does not perceive the discontinuities.
In terms of the models and brands, 50 to 70 fixed images or frames per second, whose succession gives the sensation of movement, can be generated on the screen of a portable computer. Said frames can be alternately directed, one by one or in small groups, towards the left eye or towards the right eye, which achieves the effect of stereoscopic vision without reducing resolution from the image.
The block diagram of the invention can include a digital image generating system connected to a liquid-crystal screen and to an image synchronization block which in turn connects with said screen through a angle generator system.
The invention is applicable to all types of screens, luminescent or not, monochromic or color screens, as long as they have the viewing characteristics (directable angle) of the liquid-crystal (LCD) screens, such as luminescent, TFT, phosphorescent, electromechanical type screens, etc.
The invention is also applicable to three-dimensional cathode ray tube (CRT) screens of those that most televisions and computers use, and even slide projectors and any other method of image generation in general. Therefore, in front of the television monitor, generated image or the like, a transparent liquid-crystal screen, whose pixels will be directed towards the viewer's right eye and left eye as stated above, is placed. Of course, in this case, the television monitor or generated images must emit stereographic images that will have to be synchronized with the direction that we carry out on the cited transparent screen.
The synchronization between a television, frame and the electronic directionalization towards the left eye or the right eye can be achieved in various ways, but one of great versatility, given that it releases to he transparent screen electrically connected to the television monitor, is the following: the electronic beam that generates the light spots on a CRT screen, begins its exploration in the top left corner and ends in the bottom right corner. By detecting the passing of the last spot of the image, the end of a frame is obtained. This detection may be obtained with a type of optical pencil which upon being activated directs the transparent LCD screen in one direction or the other. This system is valid for distances that do not exceed a distance of 1 or 1.5 meters between the viewer and the television monitor. For larger distances there is the possibility of approaching the LCD screen to the viewer and moving it away from the television monitor, in which case the connection between said LCD screen and the “optical pencil” applied to the monitor can be done by means of cables, ultrasound or infrared rays.
Another solution to direct the pixels of the liquid-crystal screen consists of placing behind it two angularly arranged lenses, placing behind each lens a mask or polarizer and a lamp, in such a way that the illumination of a lamp produces a light beam towards the viewer's left eye and the illumination of the other lamp generates another light beam towards the right eye. In this case, the cited lamps must turn on and turn off alternately and synchronical
Kelley Chris
Klauber & Jackson
Philippe Gims
LandOfFree
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